This relates generally to graphics processing for computers and particularly to depth offset compression.
In depth offset compression, the minimum depth (Zmin) and maximum depth (Zmax) of a tile or rectangular region of pixels is stored. Each sample's depth is encoded relative to either Zmin or Zmax. The remaining bits are used to store a mask that indicates whether each sample is taken relative to Zmin or Zmax and encodes the so-called “residual bits” that specify the difference value for each sample relative to either Zmin or Zmax. Existing depth offset compression techniques use the same number of bits per residual.
Compression methods are becoming increasingly important for graphics hardware architectures because they may reduce the power and/or increase performance. Compression is successful if all the residuals are small enough to fit within the desired bit budget of the tile. Otherwise the data may be stored in uncompressed form or compressed using some other technique. The same depth offset compression can also be used on individual color components for color buffer compression.